I can’t see anything blindingly obvious that would cause problems. What specifically is not working in IE6?
BTW, you also have the suckerfish_ie.js script linked in your theme. That is pointless since the plugin is already loading the Superfish script which includes the suckerfish system.
in fact, in FF and IE7 or IE8, all works great, but just in IE6, when mouse hover the item which include the son item, all the structure of the menu is mess up. Could you just look around, and give me some advise
Oops, your post somehow slipped past me! Are you still needing assistance? Your menu seems to be working fine in Chrome and I couldn’t immediately see any reason it would work in IE6.